Original cube side = 12 cm. Number of 3-cm cubes along each edge = 12 ÷ 3 = 4.<br>
Total small cubes = 4&sup3; = 64.<br><br>
Surface area of one small cube = 6 × 3&sup2; = 54 cm&sup2;<br>
Total SA of 64 small cubes = 64 × 54 = 3,456 cm&sup2;<br><br>
Original cube SA = 6 × 12&sup2; = 864 cm&sup2;<br><br>
Ratio = 3,456 : 864 = 4 : 1<br><br>
Final Answer: 4 : 1